Thermosetting diallyl methylphthalate resins and process for their preparation

ABSTRACT

1. A THERMOSET DIALLYL METHYLPHTHALATE CURED RESIN COMPRISING AT LEAST 70 MOL PERCENT OF STRUCTURE UNITS DERIVED FROM A MONOMER SELECTED FROM THE GROUP CONSISTING OF DIALLY METHYLISOPHTHALATE AND DIALLY METHYLTEREPHTHALATE AND NOT MORE THAN 30 MOL PERCENT OF STRUCTURAL UNITS DERIVED FROM A COMPOUND SELECTED FROM THE GROUP CONSISTING OF 1,2-POLYBUTADIENE, VINYL COMPOUNDS, AND ALLYL ESTERS OF MONO-OR POLY-BASIC ACIDS OTHER THAN SAID MONOMERS.

United States Patent 3 840 502 THERMOSE'ITING nIALLizL METHYLPHTHALATERESINS AND PROCESS FOR THEIR PREPARA- TION Kiyokazu Tsunawaki, KatsuhisaWatanabe, Shigeru Sasama, Yuzo Aito, and Kiyoshi Nawata, Tokyo, Japan,assignors to Teijin Limited, Osaka, Japan No Drawing. Filed Oct. 10,1972, Ser. No. 296,015 Int. 'Cl. C08f 15/16 U.S. Cl. 260-785 UA 9 ClaimsABSTRACT OF THE DISCLOSURE This invention relates to a novelthermosetting resin and a process for its preparation. The thermosettingdiallyl methylphthalate resins of this invention have markedly improvedthermal stability and chemical resistance as compared with the knownthermosetting diallyl phthalate resins and superior electrical andmechanical characteristics comparable to those of the known diallylphthalate reslns.

It has previously been known to provide thermosetting diallyl phthalateresins by polymerizing diallyl esters of dibasic acids such as diallylterephthalate, diallyl isophathalate or diallyl ortho-phthalate. Inorder to provide desirable physical properties, a prepolymer is producedby reaction of diallyl phthalate in a first stage, and the prepolymercontaining residual unsaturated bonds is polymerized usually in thepresence of a peroxide catalyst in a second stage to form thethermosetting resins.

Since the diallyl phthalate resins have excellent thermal stability,electrical properties and mechanical properties, they find wide utilityas decorative sheets or component parts of electrical communicationdevices. However, their use is limited because of their inferiority inchemical resistance, for example resistance to alkali hydrolysis.

Diallyl isophthalate resins having relatively good thermal resistancehave the defect that prepolymers used for their production and moldingmaterials based on these resins have extremely poor storage stability.As is well known, when a diallyl isophthalate prepolymer is stored for 6months at room temperature in the absence of an initiator, its molecularweight increases to two to three times, and the flow characteristics ofthe prepolymer become extremely poor. When heated at 50 C., theprepolymer is partially gelled in several days and cannot be used as acure molding material.

It has now been found that novel resins obtained by polymerizing diallylesters of isophthalic acid or terephthalic acid containing methyl groupsdirectly bonded to the aromatic ring have excellent electricalproperties and mechanical properties the same as in the conventionaldiallyl phthalate resins and also possess markedly improved resistanceto alkali hydrolysis, thermal stability and storage stability.

Thermosetting diallyl methylphthalate resins composed of structuralunits derived from a monomer selected from diallyl methylisophthalateand diallyl methylterephthalate have been totally unknown. We have foundthat these unknown resins have the excellent improved properties3,840,502 Patented Oct. 8, 1974 as described above as compared with theknown thermosetting diallyl phthalate resins composed of structuralunits derived from diallyl phthalates.

It is therefore an object of this invention to provide a novelthermosetting diallyl methylphthalate.

Another object of this invention is to provide a thermosetting diallylmethylphthalate resin having the desirable electrical and mechanicalproperties of the known thermosetting diallyl phthalate resins and alsohaving remarkably improved thermal stability and chemical resistance.

Still another object of this invention is to provide a process forpreparing the novel thermosetting diallyl methylphthalate resins havingthe improved properties described above.

Many other objects and the advantages of the present invention willbecome apparent from the following description.

The thermosetting diallyl methylphthalate resins of the presentinvention can be prepared by polymerizing at least one member selectedfrom the group consisting of:

(l) diallyl methylisophthalate,

(2) diallyl methylterephthalate,

(3) a homoor co-prepolymer having residual unsaturated bonds which isderived from a monomer selected from the group consisting of diallylmethylisophthalate and diallyl methylterephthalate, and

(4) a co-prepolymer having residual unsaturated bonds composedpredominantly of structural units derived from a monomer selected fromthe group consisting of diallyl methylisophthalate and diallylmethylterephthalate.

At this time, the above member may be copolymerized together with aminor amount, for example, not more than 30 mol percent, of a comonomercopolymerizable with said member to provide a thermosetting diallylmethylphthalate resin containing structural units derived from such acomonomer.

The diallyl methylisophthalate and diallyl methyl terephthalate used inthe present invention can be prepared by a method known per see. Forexample, they are prepared (a) by dehydrohalogenation of halogenides ofmethylisophthalic acid or methyl terephthalic acid and allyl alcohol,(b) by reaction of alkali metal salts of methyl isophthalic acid ormethyl terephthalic acid with allyl halogenides, and (c) byester-interchange reaction of lower alkyl esters of methyl isophthalicacid or methyl terephthalic acid using allyl alcohol. The methylisophthalic acid and methyl terephthalic acid used here can also beprepared by a known method. Usually, they are prepared by oxidation oftrialkylbenzenes, for example pseudocumene, under mild conditions.

The prepolymers (3) and (4) described above can be produced by methodsknown per se for producing prepolymers of diallyl phthalate. Forexample, the prepolymer (3) can be prepared by heating diallylmethylisophthalate and/ or diallyl methylterephthalate in the presenceor absence of a solvent and in the presence or absence of a free radicalinitiator. The reaction is stopped beore the gellation of the reactionmixture occurs, preferably when about 15-50% of the diallylmethylisophthalate and/or diallyl methylterephthalate has been consumed,and the unreacted material or residual solvent are separated from thereaction mixture.

The reaction temperature can be varied over a wide range according tothe type of the free radical initiator or the presence or absence of thesolvent and also its kind or amount, and is generally from to 200 C.When a peroxide is used as the free radical initiator, it is convenientto use an organic solvent and perform the reaction at to C. under theconditions of total reflux.

The reaction pressure may be varied over a wide range, but preferablythe reaction is carried out at atmospheric pressure.

The preferred solvents used in the above reaction are lower aliphaticalcohols having 1 to carbon atoms, aromatic hydrocarbons such asbenzene, toluene, xylene, ethylbenzene or isopropylbenzene, and loweraliphatic ketones such as acetone, methyl ethyl ketone or methylisobutyl ketone. The reaction temperature is controlled by using asuitable amount of such a solvent, and the reaction system can bemaintained uniform during polymerization. The free radical initiator maybe an organic peroxide such as benzoyl peroxide, t-butyl hydroperoxideor t-butyl perbenzoate, an azo compound such as 2,2-azobisisobutyronitrile or another substance having a similar effect. Theamount of the free radical initiator is usually from 0.05 to 5% byweight based on the amount of the monomer.

The co-prepolymer (4) can be prepared by carrying out the above reactionof forming the homoor co-prepolymer (3) in the copresence of a minoramount of a comonomer copolymerizable with the diallylmethylisophthalate or diallyl methylterephthalate. An example of theco-prepolymer (4) is a prepolymer composed of at least 80 mol percent,preferably at least 90 mol percent, of structural units derived from amonomer selected from diallyl methylisophthalate and diallylmethylterephthalate and not more than 20 mol percent, preferably notmore than mol percent, of structural units derived from an allyl esterof a monoor polybasic acid other than said monomer.

Specific examples of the allyl ester of a monoor polybasic acid are diortri-allyl esters of aromatic polybasic acids such as phthalic acid,isophthalic acid, terephthalic acid or trimellitic acid; polyallylesters of aliphatic polybasic acids, such as maleic acid, fumaric acidor sebacic acid; allyl esters of mono-basic acids such as methacrylicacid or benzoic acid. Of these, diallyl isophthalate, diallylterephthalate are especially preferred.

The homoor co-prepolymers (3) and (4) are useful for laminatingpurposes. According to the present application, therefore, there can beprovided a prepolymer of diallyl methylphthalate composed of at least 80mol percent, preferably at least 90 mol percent, of structural unitsderived from a monomer selected from diallyl methylisophthalate anddiallyl methyl terephthalate and not more than 20 mol percent,preferably not more than 10 mol percent, of structural units derivedfrom an allyl ester of a monoor poly-basic acid other than said monomer.This prepolymer is also a novel prepolymer, and can be used as amaterial for the production of the thermosetting diallyl methylphthalateof this invention, and also has valuable applications by itself.

The homoor co-prepolymers (3) and (4) preferably have a number averagemolecular weight of about 3,000 to about 30,000. This prepolymer is asolid thermoplastic polymer containing residual unsaturated bonds. Byfurther heating of the prepolymer, a thermosetting resin havingcross-linkages can be easily produced.

The prepolymer, for example a prepolymer from diallyl-4-methylisophthalate, has very good storage stability, and even when allowed tostand for six months at room temperature, it hardly changes in molecularweight or flow characteristics. Therefore, this is a very stableprepolymer which can provide a molding material of good flowcharacteristics.

In the present invention, the thermosetting diallyl methylphthalates canbe produced by polymerizing or copolymerizing at least one memberselected from (1), (2), (3), and (4). The polymerization may beperformed in the copresence of a comonomer copolymerizable with themember described.

Examples of such a comonomer include allyl esters of monoor poly-basicacids other than the diallyl methylisophthalate and diallyl methylterephthalate, vinyl compounds such as styrene, methyl methacrylate orglycidyl methacrylate, and 1,2-polybutadiene. Of course, diallylisophthalate, diallyl terephthalate, 1,2-polybutadiene are especiallypreferred. The 1,2-polybutadiene is a polybutadiene in which therepeating units consist predominantly of 1,2-form units. Those having atleast 60%, especially at least of l,2-form units can be used preferably.The molecular weight of the polybutadiene is not critical in the presentinvention, but usually, those having a molecular weight of 500 to 10,000(namely, ranging from a liquid to semi-liquid or solid) are used.

Preferably, the resulting thermosetting diallyl methylphthalate resincontains at least 60 mol percent of structural units derived from amonomer selected from the group consisting of diallyl methylisophthalateand diallyl methylterephthalate, based on the total amount of the resin.The more preferred content of these structural units is at least 70 molpercent, especially at least 80 mol percent, and in particular at leastmol percent.

The polymerization of the member selected from (1) to (4) is carried outby heatingthe reaction system. This reaction is a curing reaction, andcan be performed, for example at -200 C., preferably 180 C., atatmospheric pressure or at an elevated pressure of not more than 700kg./cm.

In order to perform the final curing with good efficiency it ispreferred to use a free radical initiator. An organic peroxide ispreferred as the initiator. Examples of the organic peroxide areperbenzoic acid esters, benzoyl peroxide, dicumyl peroxide or t-butylhydroperoxide.

The amount of the free radical initiator is usually from 0.5 to 5.0% byweight based on the total amount of the reactants.

Whenever required, an internal mold releasing agent, a filler, acoloring agent, a polymerization inhibitor, a reinforcing agent, a fireretardant or another additive can be used in this curing reaction.Examples of the mold releasing agent are lauric acid, stearic acid,calcium stearate, zinc stearate and silicone resins. Examples of thefiller are calcium carbonate, silica, alumina and kaolinite. Examples ofthe coloring agent are carbon black, ceramic black, phthalocyanine blueand phthalocyanine green. Examples of the polymerization inhibitor arehydroquinone, tert.-butyl catechol and 2,5-ditert.butyl hydroquinone.Examples of the reinforcing agent are glass fibers, boron fibers, carbonfibers, asbestos fibers, pulp, polyester fibers, and polyacrylic fibers.Examples of the fire retardant include antimony oxide and tris(2,3-dibromopropyl) phosphate.

The thermosetting diallyl methylphthalate resins of this invention haveespecially superior thermal stability and chemical resistance ascompared with the known diallyl phthalate resins. Usually, they show aheat stability index of at least 80% and a caustic resistance of atleast 80%. This represents a marked improvement over the known diallylphthalate resins which have a thermal stability of 65% at most and acaustic resistance of at most about 70%.

The thermosetting diallyl methylphthalate resins of this invention maybe in the form of shaped articles or shaping resin compositions.

The heat stability index and caustic resistance of the resins weredetermined by the following methods.

THERMAL STABILITY (1) Preparation of test pieces Rectangular pieces each4 mm. thick, 10 mm. wide and 50 mm. long were cut out from thethermosetting resin, and used for the test.

(2) Test of thermal stability An air-circulating heating device was setat 260 C., and the test pieces were kept therein for 10 hours with caretaken not to bring the test pieces into contact with one another.

(3) Heat stability index The weight (W) of the heated test pieces wasdetermined, and the thermal stability was evaluated by the percentretention as against the weight (W of the test pieces beforeheat-treatment.

The heat stability index (HSI) is as follows:

W Wu

HSI (percent): X100 CHEMICAL RESISTANCE (1) Preparation of test piecesThe same test pieces as used in the thermal stability test were used.

(2) 10 parts by weight of caustic soda solution was dissolved in 90parts by weight of pure water to prepare a 10% aqueous solution.

(3) Chemical resistance test Each of the test piece was immersed in the10% aqueous caustic soda solution prepared above in an amountcorresponding to 10 volume/weight times the amount of the test piece,and placed in a constant temperature oil bath maintained at 100 C. for50 hours.

(4) Measurement of hardness and caustic resistance Each of the testpiece was then washed with flowing water for 30 minutes to wipe offwater adsorbed thereto using a cotton cloth. The test piece was thenmaintained at a constant temperature of 25 C. and a relative humidity of60% for 10 minutes. Immediately then the Barcol hardness of the specimenwas measured using Impressor No. 935 (Barber-Colman Company).

The chemical resistance (alkali resistance) of the test piece wasevaluated by the ratio of the Barcol hardness (H) of the treated testpiece to the Barcol hardness (H of the test piece before treatment withcaustic soda.

That is to say, the caustic resistance (CR) was calulated by thefollowing equation.

CR (percent) g X 100 The caustic resistance is preferably more than 80%.If the test piece has a caustic resistance of more than 90%, it isjudged to have extremely good resistance to alkali.

The following Examples are given to illustrate the present invention.All parts are by weight unless otherwise specified.

EXAMPLE 1 Preparation of Prepolymers I-A: A mixture of 100 parts ofdiallyl 4-methylisophthalate having a boiling point of 129131 C. at 1.5mm. Hg and 0.22 part of benzoyl peroxide was heated from roomtemperature to 110 C. in the course of one hour with stirring in anatmosphere of nitrogen. The reaction was performed for '4 hours at 110C1 C. The reaction mixture was then cooled to 30 C., and the stirringwas stopped. The reaction mixture having a viscosity at 25 C. of 410centipoises was withdrawn, and poured into about 5 times its volume ofmethanol. The unreacted monomer and the remaining free radical initiatormoved to methanol, and the resulting prepolymer was precipitated. Freshmethanol was added to the precipitate, and the mixture was stirredthoroughly, The separated solid was pulverized and dried to form 29parts of a prepolymer of diallyl 4-methylisophthalate. This prepolymerwas in the form of white powders having an iodine value of 76 and anumber average molecular weight of 9000.

LE: A mixture of 100 parts of diallyl methylterephthalate having aboiling point of 129130 C. at 1.5 mm. Hg, 35 parts of sec.-butyl alcoholand 2.5 parts of benzoyl peroxide was heated to 100 C. for 2 hours in anatmosphere of nitrogen with stirring. The reaction mixture was thencooled to 30 C., and the stirring was stopped. The reaction mixturehaving a viscosity at 25 C. of 280 centipoises was withdrawn, and pouredinto about 5 times its volume of methanol with stirring. The unreactedmonomer, sec.-butyl alcohol, and the remaining free radical initiatorwere moved to methanol, and the resulting prepolymer was precipitated.This precipitate was washed with methanol and dried to yield 44 parts ofa prepolymer of diallyl methylterephthalate. This prepolymer was in theform of white powders having an iodine value of 69 and a number averagemolecular weight of 6700.

IC: Diallyl 4-methylisophthalate (30 parts), 70 parts of of diallylmethylterephthalte, 1.2 parts of benzoyl peroxide and 100 parts ofn-propanol were mixed with one another, and heated for 5 hours at atotal reflux temperature (98 to 100 C.) while stirring in an atmosphereof nitrogen. The reaction mixture was cooled to room temperature, andallowed to stand for about 5 hours. The white highly viscous layer thatseparated down to the bottom was dissolved in 25 parts of acetone, andthe resulting solution was poured into 10 times its volume of methanolto precipitate a prepolymer. The product was thoroughly washed,separated, and dried to form white powder of the prepolymer having asoftening point of 65 to C., an iodine value of 67 and a number averagemolecular weight of 7100 in a yield of 32%. Gas-chromatographic analysisof all the monomers recovered showed that the composition of themonomeric units in the prepolymer substantially corresponded with thatof the monomers used.

I-'D: Diallyl 4-methylisophthalate (40 parts), 60 parts of diallylmethylterephthalate, 1.2 parts of benzoyl peroxide and parts ofn-propanol were mixed with one another, and heated for 3 hours at atotal reflux temperature (98100 C.) with stirring in an atmosphere ofnitrogen. The reaction mixture was cooled to room temperature, and thewhite highly viscous layer that separated down to the bottom wasdissolved in 25 parts of acetone, and the resulting solution was pouredinto about 10 times its volume of methanol to precipitate a prepolymer.The product was washed and dried to form a white solid having asoftening point of 50 to 90 C., an iodine value of 60 and a numberaverage molecular weight of 5900 in a yield of 24%.

I-E: Diallyl 4-methylisophthate '(50 parts), 50 parts of diallylmethylterephthalate, 1.5 parts of benzoyl peroxide and 100 parts ofmethyl ethyl ketone were mixed with one another. With vigorous stirring,the mixture was heated for 7.5 hours at a total reflux temperature(79.5- 81.5 C.). The reaction mixture was then cooled to roomtemperature, and poured into five times its volume of methanol toprecipitate a prepolymer. The product was thoroughly washed with freshmethanol, and dried to form 40 parts of white powders of the prepolymerhaving an iodine value of 77 and a number average molecular weight of5600.

I-F: A mixture of 70 parts of diallyl 4-met-hylisophthalate, 25 parts ofdiallyl methylterephthalate, 5 parts of diallyl maleate having a boilingpoint of 93.7 C. at 1 mm. Hg, and 0.1 part of benzoyl peroxide washeated from room temperature to 100 C.. in the course of one hour withstirring in an atmosphere of nitrogen. During this time, additional 0.1part of benzoyl peroxide was added little by little. The mixture wasthen reacted at a temperature of 100:1.0 C. for 5 hours. The mixture wasthen cooled to 30 C., and the stirring was stopped. A colorlesstransparent reaction mixture having a viscosity at 30 C. of 270centipoises was withdrawn and poured into 2 times its volume ofmethanol. The resulting mixture was heated to 55 to 60 C., and theprepolymer layer which became flow'able was stirred, followed byextracting methanol-soluble substances other than the a white powderyprepolymer having a softening point of 70 to 105 C. and a number averagemolecular weight of 10,800 in a yield of 29%. It was confirmed from theD /D ratio that the prepolymer obtained contained 40%, based on themonomers, of unsaturated bonds, and

prepolymer. The supernatant liquid was removed, and from the results ofalkali hydrolysis the composition of fresh methanol was used first in anamount 2 times the the monomeric units in the prepolymer was about 80:20volume of the prepolymer layer and finally in an amount (:diallyl methylterephthalatezdiallyl phthalate). equal to the prepolymer in order toremove the methanol- II: The prepolymer of diallyl phthalate used in thesoluble substances by extraction. The prepolymer layer followingExamples and Comparative Examples had an was cooled, solidified,pulverized, and dried at room temiodine value of 50 and a number averagemolecular perature under reduced pressure. A prepolymer having an weightof 14,000. iodine value of 69 and a number average molecular II: Theprepolymer of diallyl is-ophthalate used in weight of 7800 was obtainedat a conversion of 26%. the following Examples and Comparative Exampleshad From the nuclear magnetic resonance spectrum of the an iodine valueof 65 and a number average molecular prepolymer, its alkali hydrolysisand the gas-chromatoweight of 11,000. .graphic analysis of substancesother than the recovered EXAMPLE II prepolymer, it was confirmed thatthe composition of the monomeric units in the prepolymer substantiallycorre- Preparation of Cured Resins Using Prepolymer sponded with diallyl4-methylisophthalate:diallyl meth- 2O ylterephthalatezdiallylmaleate=60:20:20. 95 parts 0f the prepolymer p p 111 Example I-G: Amixture of 95 parts of diallyl 4-methyliso- 5 p s dlallyltmethylisophthalate. 2 pa 9 phthalate, 5 parts of allyl benzoate and 0.3part of tert. dlcumyl PerOXlde and 300 p fi acetone were limited Inperbenzoate was heated from room temperature to a kneader, and thenkneaded With a roller heated at 100 130 C. in the course of 2 hours withstirring in an atmos- Tl'le mlXturP Was then dfled for 12 hours to m aphere of nitrogen, and then reacted at a temperature of moldlllgmaterlal- 130+1.0 c. for -4 hours. The reaction mixture was then emolding material was maintained for 0 m u es cooled to room temperature,and the reaction mixture at 150 g 6111-2 in a mold heated at 170 C. toform a together with about 5 times its volume of methanol was curedproduct. fed by a pump to a colloid mill (the clearance between 9 P tsOf the prepolymer prepared in Example the rotary body and the fixed body0.01 inch, speed 3600 I-B, 5 parts of diallyl methylterephthalate and 2parts of r.p.m., flow rate of 757 liters/hr.). The mixture was dicumylperoxide and 300 parts of acetone were mixed cooled to 5 C., and thesolid substance was recovered in the same way as in Example II-(l) toform a molding by filtration. It was washed with cold methanol, andmaterial. The material was cured in the same way as mendried at reducedpressure at room temperature. From tioned in (1) above. the D /D ratio(the ratio of adsorbance at 1645 (3) to (5) In quite the same way as inExample II- cm." to that at 1600 cm."" of the infrared absorption (1),cured products shown in Table I were prepared spectrum, it was confirmedthat the resulting white powu ing th prepolymer prepared in ExamplesI-C, L1) and dery prepolymer contained about 35%, based on the LErespectively, monomers, of unsaturated bonds. The results of its alkali(5 For comparison, the procedure f Example H (1) hydrolysis showed thatthe composition of the monomeric was repeated except that diallylphthalate and the umts of the prepolymer was diallyl4-methY11SPhtPa1ate= polymer derived from diallyl phthalate shown inExample 'allyl benzoat6=97i3' The number molecltlar Welght of I-(l) wereused instead of diallyl 4-methylisophthalate the prepolynier was 7600and i converslon was and the prepolymer derived from diallyl4-methylisoph- I-H: A mlxture of 90 parts of diallylmethylterephthalthalate in Example H41). f zg many; Phthalate g ir z g(7) In quite the same way as in (1), except that diallyl 0X1 8 and 1Parts 0 lsopropano was or isophthalate and the prepolymer derived fromdiallyl isoat a total reflux temperature (82.5 to 84.3 C.) with stirh hl t h E l I I d t d f ring in an atmosphere of nitrogen. The reactionmixture t a a e s m Xamp e were use ms ea O was then cooled to C and wasthen poured into 300 50 diallyl 4-methyl1sophthalate and the prepolymerderived parts of methanol heated at 45 C. with vigorous stirring. fromdiallyl, 4'methyhsophthalate used 111 Example 11- The precipitate formedwas washed, dried, and dissolved (I), respectwelx', in 0 parts f acetoneThe resulting Solution was poured The heat stabllity indices and thecaustic resistances of into 200 parts of methanol heated at 45 C. andvigorously the cured Pmducts Qbtamed 1n Examples t0 stirred. Theprecipitate formed was thoroughly washed w r measured, and the resultsshown In Table I below with methanol, recovered by filtration and driedto yield were obtained.

TABLE 1 Monomer contents of the cured product (moi. percent) DiallylDiallyl Heat 4-methy1- methyl- Contents of components other stabilityCaustic Example isophthalterephthan the monomers in the index resistancenumber ate thalate preceding column (moi. percent) (percent) (percent)98 94 9G 89 97 9o 97 50 97 91 (diallylphthalate).-. 64 69 100(diallylisophthalate)- 94 86 TABLE 2 X100 (percent) Resin hours 100hours No. 1 of Table 1 98 94 N0. 6 of Table 1 64 50 No. 7 of Table 1 9479 Other properties of the cured resins obtained in No. 1, No. 6 and No.7 shown in Table 2 were measured, and the results are shown in Table 3.

It is seen from the results obtained above that whilethe flowcharacteristics of the diallyl isophthalate prepolymer become very pooras a result of heat-treatment, the flow characteristics of the diallyl4-methylisophthalate prepolymer hardly change, and therefore that thelatter is a very stable prepolymer.

EXAMPLE III Preparation of Cured Resins Using Monomers Only (8) Auniform solution consisting of 50 parts of diallyl 4-methylisophthalate,50 parts of diallyl methyltere phthalate, 1 part of benzoyl peroxide and2 parts of dicumyl peroxide was charged into a casting mold which wasformed between two opposing glass plates disposed at a distance of 4 mm.and which contained four glass cloths, and impregnated into the glasscloths. Thereafter, the casting mold was heated from 80 C. to 160 C. ata TABLE 3 rate of 03 C./min. to form a cured product.

Basin The cured product had a flexural strength of 22.5 1 N0 6 I kg./mm.and -a flexural modulus of 805 kg./mm. It was (p (9 a toughglass-reinforced cured resin plate. Pmpemes pans) pans (9) to (11)Glass-reinforced cured resin plates (glass Temperature at vhich adecrease in 311 276 303 content 50% by weight) of the compositions shownin nit ttfiit fiitt emrataiaia'i ebiii::1: 260 160 238 Table 5 eproduced in quite the same w y n ey garcolilliargltlless 7 4 ousproportions of monomers. The heat stability index gi g i igflg 'fi31x10" ggxmw 69x10 and caustic resistance of each of the resin platesobtained %}riac$ esistiv ity flvutug 2.2X1 0 8.0X1301; were measured,and the results are shown in Table 5. It is ilfifitfifi 33111;): -II o.021 0. 0&2 0. air See11 frm the results obtijlined P the cured resins fResistance to are (second) 129 1 8 cording to the present invention havevery superior 30 thermal stability and chemical resistance.

TABLE 5 Monomer contents in the cured resin (mol. percent) DiallylDiallyl ylmethyl- Heat Caustic isophthalterephthal- Content of othermonomerin the stability resistance Example ate ate cured resin (mol.percent) (percent) (percent) so 50 95 as 100 9c 90 95 5 (glycidylmethacrylate) 93 87 100 (diallyl phthalate).. 59 66 -It is confirmedtherefore that the cured resin derived from diallyl 4-methylisophthalatehas excellent electrical properties and surface hardness.

Each of the diallyl 4-methyl1sophthal'ate prepolymer EXAMPLE IVdescribed in Example LA and the diallyl isophthalate prepolymerdescribed in Example I4 was treated at C. One gram each of theseprepolymers was set in a flow tester held at 100 C., and under apressure of 100 kg./ cm the speed of displacement of the plunger of theflow tester [amount of displacement (mm.)/min.] was measured. Thepercentage of the speed of displacement based on that of the prepolymerbefore the above-mentioned treatment was calculated. The results areshown in Table 4.

(12) A uniform viscous solution having a viscosity at 25 C. of 4200centipoises and consisting of 40 parts of the prepolymer derived fromdiallyl 4-methylisophthalate prepared in Example I-A, parts of diallyl4-methylisophthalate and 2 parts of tertiary butyl perbenzoate waspoured into a casting mold formed between two glass plates disposed at adistance of 4 mm. After degassing, the casting mold was heated from C.to 160 C. at a rate of 0.25 C./min. to form a colorless transparentcured resin.

TABLE 4 (13) to (15) Cured resins of the composition shown in PrepulymerTable 6 were obtained in quite the same way. The heat Dianyl stabilityindex and caustic resistance of each of these methyliso- Diallyliso- 60cured resins, as shown in Table 6, were extremely Treating conditionsphthfllate Dhthalate superior. 50 C., 24 hours, percent 95. 9 93- 5 500., 72 hours, percent 80. 0 60.9 50 0., 120 hours, percent 62. 0 28. 3

TABLE 6 Monomer contents in the cured product (mol. percent) DiallylDiallyl He Caustic 4-methylmethylstability resistisotereph- Content 01other monomer in the index ance Example phthalate thalate cured resin(mol. percent) (percent) (percent) 100 96 35 50 15(diallylisophthalate)98 40 40 20 (1,2-polybutadiene having mo- 98 91 lecular weight 2,000,liquid). 95 5 (styrene) 86 88 1 1 EXAMPLE v (16) 95.3 parts of theprepolymer prepared from diallyl methylterephthalate in Example IB, 4.7parts of diallyl isophthalate and 2 parts of dicumyl peroxide were mixedin a kneader. The mixture obtained was heated for 15 minutes at 150 C.and 500 kg./cm. and further maintained at 115 C. for hours to completeits curing.

(17) A cured resin having the composition shown in Table 7 was producedin the same way as in (16) above using the precopolymer obtained inExample IF (diallyl 4-methylisophthalate/diallylmethylterephthalateldiallyl maleate=60/ 20/ 20) (18) A cured resinhaving the composition shown in Table 7 was produced in the same way asin (16) above using the precopolymer obtained in Example [-6 (diallyl4-methylisophthalate/allyl benzoate=93/7).

(19) A cured resin having the composition shown in Table 7 was producedin the same way as in 16) above using the precopolymer prepared inExample IH (diallyl methylterephthalateldiallyl phthalate=80/ 20) (20) Acured resin having the composition shown in Table 7 was produced in thesame way as in (16) above using the precopolymer (diallyl4-methylisophthalate/ diallyl-methylterephthalate=40/ 60) obtained inExample ID, the prepolymer from diallyl isophthalate described inExample IJ and triallyl trimellitate.

The heat stability index and caustic resistance of each of the curedresins obtained above are shown in Table 7. It is seen from these datathat the cured resins according to the present invention exhibitextremely good thermal resistance and resistance to alkali.

What is claimed is:

1. A thermoset diallyl methylphthalate cured resin comprising at leastmol percent of structural units derived from a monomer selected from thegroup consisting of diallyl methylisophthalate and diallylmethylterephthalate and not more than 30 mol percent of structural unitsderived from a compound selected from the group consisting of1,2-polybutadiene, vinyl compounds, and allyl esters of monoorpoly-basic acids other than said monomers.

2. The resin of claim 1 which has a heat stability index of at least 3.The resin of claim 1 which has a caustic resistance of at least 80%.

4. The resin of claim 1 wherein said allyl ester of monoor poly-basicacid is selected from the group consisting of allyl methacrylate, allylbenzoate, diallyl phthalate, diallyl isophthalate, diallyl terephthalateand triallyl trimellitate.

5. The resin of claim 1 wherein said vinyl compound is selected from thegroup consisting of styrene, methyl methacrylate and glycidylmethacrylate.

6. The resin of claim 1 wherein the structural unit derived from saidmonomer is at least 80 mol percent.

7. A diallyl methylphthalate prepolymer comprising at least 80 molpercent of structural units derived from a monomer selected from thegroup consisting of diallyl methyl isophthalate and diallylmethylterephthalate and not more than 20 mol percent of structural unitsderived from an allyl ester of a monoor poly-basic acid other thandiallyl methylisophthalate and diallyl methylterephthalate.

8. The prepolymer of claim 7 wherein said prepolymer has a numberaverage molecular weight of about 3000 to 30,000.

9. The resin of claim 1 which is in the form of a shaped article.

TABLE 7 Monomer contents of the cured resin (mol. percent) DiallylDiallyl Heat 4-methy1- methylstability Caustic isophthatereph- Contentsof other monomers index resistance Example late thalate (mol. percent)(percent) (percent) 16 95 5 (diallyl isophthalate) 95 5 (diallylmaleate) 89 83 37 60 3 (allyl benzoate) 88 84 92 narra es 1e- 83 35 {5(mamii tri ellitztz) .I 94 89 References Cited UNITED STATES PATENTS2,501,610 3/1950 Morris et al 26078.4 3,390,116 6/1968 Porret 260-3283,326,966 6/1967 Renckhoif et al. 260-475 2,445,627 7/1948 Morris et al.260468 2,578,312 12/1951 Miller et al 260-475 2,433,616 12/1947 Marpleet al. 260-78.4

JOSEPH L. SCHOFER, Primary Examiner I. KIGHT, Assistant Examiner US. Cl.X.R.

2.6078.4 UA, D, 873

UNITED STATES PATENT OFF ICE CERTIFICATE OF CORRECTION Patent No. 3,840,502 Dated October 8, 1974 lnventor(s) KIYOKAZU TSUNAWAKI ET AL Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

In the Heading, insert patentees' Foreign Application PriorityInformation as follows:

' Japanese Application No. 46-81151/ 71, filed October 14, 1971 JapaneseApplication No. 47-56804/72, filed June 9, 1972.

Sigmed and sealed this 7th day of January 1975.

(sis-LL Attest:

HcCOY M. GIBSON JR. C. MARSHALL DANN Attesting'Officer CommissionerofPatents F ORM PO-105O (10-69) USCOMM-DC 60376-P 6B US, GOVERNMENTPRINTING OFFICE i I... 0-3"-33,

1. A THERMOSET DIALLYL METHYLPHTHALATE CURED RESIN COMPRISING AT LEAST70 MOL PERCENT OF STRUCTURE UNITS DERIVED FROM A MONOMER SELECTED FROMTHE GROUP CONSISTING OF DIALLY METHYLISOPHTHALATE AND DIALLYMETHYLTEREPHTHALATE AND NOT MORE THAN 30 MOL PERCENT OF STRUCTURAL UNITSDERIVED FROM A COMPOUND SELECTED FROM THE GROUP CONSISTING OF1,2-POLYBUTADIENE, VINYL COMPOUNDS, AND ALLYL ESTERS OF MONO-ORPOLY-BASIC ACIDS OTHER THAN SAID MONOMERS.